Press Hardened Steel (PHS)

Press Hardened Steel (PHS) is currently the highest-strength steel utilised in automotive body structures, serving as an "invisible armour" that shields the passenger safety cell. Through high-temperature stamping followed by rapid in-die quenching, its structural strength is elevated several times over compared to conventional steel.

⚙️ Principle: Transforming from "Soft" to Ultra-High Strength

The exceptional strength of press hardened steel is achieved through a specialised hot-forming and quenching process:

1. High-Temperature "Softening": Special boron-alloyed steel sheets (such as 22MnB5) are heated to approximately 900–950°C, transforming the material into pliable austenite that can be shaped effortlessly like dough.

2. In-Die "Quenching": While still red-hot, the blank is quickly transferred to a stamping tool for forming and is immediately cooled inside the die at an ultra-fast rate (>27°C/second).

3. Hardness "Leap": This rapid cooling alters the steel's internal microstructure into ultra-hard martensite, boosting tensile strength from the base 500–600 MPa up to 1,300–1,600 MPa or even higher. It can withstand over 10 tonnes of force per square centimetre, delivering 3 to 4 times the strength of standard steel.

🛡️ Applications: Reinforced Where It Matters Most

Owing to its higher production cost (roughly 5 to 8 times that of ordinary steel), PHS is strategically deployed across the critical occupant "safety cage".

• Cabin Core Framework: Applied to A-pillars, B-pillars, side sills, and roof rails to prevent cabin collapse during severe crashes or rollover accidents, preserving crucial survival space for occupants.

• Side Intrusion Beams: Reinforced door impact beams designed to resist cabin penetration during side-impact collisions.

🚀 The Next Frontier: Entering the 2,400 MPa Era

The automotive industry continues to advance material engineering to build lighter vehicle architectures with superior crash protection.

• 2.4 GPa Grade Enters Mass Production: Spanning 2025 to 2026, manufacturers such as Dongfeng (Yijing X9), FAW (Hongqi), and Chery have announced pioneering applications of 2,400 MPa-grade press hardened steel. Compared to the 2.0 GPa tier, tensile strength is boosted by 15%, crash energy absorption improves by over 10%, and component weight is reduced by 5% to 10%.

⚠️ Important Repair Precautions

Following an accident, applying heat, traditional panel beating, or conventional electric welding to PHS structural components is strictly prohibited. Doing so irreversibly damages the material's microstructural integrity and severely degrades its strength, leaving it incapable of offering adequate crash protection in future impacts. Any replacement or structural repair must strictly follow OEM workshop repair manuals using factory-approved parts and procedures.